As the number of users of Internet application services based on the Internet protocol (IP) increases and various systems including wideband code division multiple access (WCDMA), CDMA2000, wireless local area network (WLAN), wireless personal area network (WPAN) systems have been introduced, it is highly required to combine various heterogeneous networks based on the IP in a next generation environment. To provide appropriate services to a user desiring to receive the services anywhere, it is required to perform an appropriate handover between wireless access systems.
In various vertical handover operations caused between wireless access systems according to a movement of a user, user network subscription conditions, and pricing policies, services to the user must not be disconnected. In addition, it is required to maintain optimum Quality of Service (QoS).
In an IP-based network, when a user moves from one network to another network and a new IP address is allocated to a terminal, previously existing application connections are finished and are required to be re-established. Accordingly, a protocol supplying IP mobility is necessary. Mobile IPv6-based handover considers IP mobility. However, in the Mobile IPv6-based handover, handover is delayed and packets are lost by a home agent and a location registration process such as binding update.
Accordingly, various Mobile IPv6 (MIPv6)-based handover methods have been suggested, but they may not appropriately consider wireless access protocol, or additional functions are added, and therefore terminal complexity may be problematically increased.
In addition, in a quick handover process based on a multi-cast in a MIPv6 wireless network, when a terminal moves to a predetermined external network, the terminal is registered in a home agent and a correspondent node by using a multi-cast address received from a gateway, a base station to which the terminal is accessed and neighboring base stations are grouped as a multi-cast group, and a handover operation is performed. Accordingly, when the terminal moves in the predetermined external network, packet delay or loss may be efficiently reduced without address change or terminal registration.
However, since the terminal wireless access protocol is not appropriately considered in a like manner of the mobile IP protocol, a procedure may be changed or a new procedure is required to be added when the wireless access protocol is used together. In addition, the vertical handover is not considered when the terminal moves to various wireless access environments, a location registration process such as binding update is required to be performed since the MIPv6 is used when the terminal moves from a home agent to an external network or moves from an external network to another external network, and therefore handover delay and packet loss may occur.
Further, in an active handover method between hybrid subscriber unit (HSU) systems, a handover method between a circuit network and a packet network has been suggested. Here, a packet data control switch (PDCS) using at least one of mobile switching center evolution-emulation (MSCe), media gateway (MGW), session initiation protocol (SIP) server, and vocoder trans-coding devices to combine the packet network and the circuit network is suggested, and a handover process between networks having different multi-cast methods is supported.
However, to support handover between various wireless access networks in the active handover between HSU systems, a PDCS for connecting the networks is necessary, where the PDCS controls signals and traffic, and therefore a new protocol between the PDCS and the wireless access system is required. In addition, since traffic is concentrated on the PDCS and handover for services that are not supported by the PDCS is not supported, terminal complexity increases to support handover by the PDCS.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.